Best account setup to contribute a VPS to someone and respect privacy

I have a $10/mth plan with digital ocean. I am looking to get another $10/mth plan vps where I will pay for this and someone else use it. What is the best method to proceed?
1) Extend my current plan to a $20/mth plan and create a droplet and give a username/pw to the other person?
2) create two digital ocean accounts, and setup the second account with a $10/mth plan. If we do it this way, how would I be able to pay and protect my privacy while protecting the other person's privacy in use and login?